1. Field of the Invention
The present invention relates to a video display apparatus, and in particular to a power supply device of a video display apparatus and a method thereof.
2. Background of the Related Art
In general, it is very important to supply stable power to a video display apparatus. Further, it is required to restrain generation of unnecessary radiative wave (in particular, higher harmonics) caused by noise or internal/external causes and prevent higher harmonics from being transmitted to other parts or other apparatus through a power line or an additional common line to guarantee operation reliability of the video display device.
For example, because higher harmonics are related to EMI (electromagnetic interference), when higher harmonics reach a video display apparatus, they can cause fatal damage to the operation of the video display apparatus. In particular, when higher harmonics generated in the power supply device are supplied to the video display apparatus, they can have a bad influence upon operation reliability or stability of the video display apparatus. In addition, because higher harmonics can be easily transmitted to other apparatus through a power line connected with the video display apparatus, higher harmonics in the power supply device have to be prevented.
FIG. 1 is a block diagram illustrating a power supply device of a video display apparatus in accordance with the related art. As shown in FIG. 1, the power supply device of the video display apparatus includes an AC power input block 101, a filtering unit 102 for removing EMI (electromagnetic interference) from AC power received through the AC power input block 101 and a rectifying section 103 for converting AC power outputted through the filtering unit 102 into DC power. A standby smoothing circuit 104 and a standby power supplier 105 supply DC power outputted from the rectifying section 103 to the video display apparatus as standby power. A harmonics suppressor 106 is for cutting off higher harmonics included in DC power (e.g., DC power including ripple element) outputted from the rectifying section 103. A main power smoothing circuit 107 and a main power supplier 108 provide DC power outputted from the harmonics suppressor 106 to the video display device as main power.
The operation of the power supply device of the video display apparatus in accordance with the related art will be described with reference to FIG. 2. FIG. 2 is a graph showing ripple waveforms (i.e., voltage waveform 201, current waveform 202) of a voltage and current inputted to the standby power supplier 105 installed at the power supply device of the video display apparatus in accordance with the related art.
First, the filtering unit 102 removes EMI by removing noise element included in the AC power applied from the AC input block 101 and outputs the noise-removed AC power to the rectifying section 103. The rectifying section 103 converts the noise-removed AC power into DC power and respectively supplies the converted DC power to the standby power smoothing circuit 104 and the harmonics suppressor 106. The rectifying section 103 can include one rectifier for the standby power and another rectifier for the main power. The DC power outputted through the rectifying section 103 includes ripple element.
The standby power smoothing circuit 104 smoothes the DC power including the ripple element and outputs the smoothed DC power to the standby power supplier 105, and the standby power supplier 105 stabilizes the smoothed DC power to supply the stabilized DC power to the video display apparatus as standby power. The standby power supplier 105 supplies the DC power including the higher harmonics to the video display apparatus.
In the meantime, the harmonics suppressor 106 cuts off the higher harmonics of the DC power including the ripple element outputted from the rectifying section 103 and outputs the higher harmonics-cut off DC power to the main power smoothing circuit 107. The main power smoothing circuit 107 smoothes the higher harmonics-cut off DC power and supplies the smoothed DC power to the main power supplier 108. Herein, the main power supplier 108 stabilizes the smoothed DC power and supplies the stabilized DC power as main power of the video display apparatus.
When the power supply device of the related art video display apparatus is in a standby power supply mode, since there is no means for cutting off the higher harmonics applied to the standby power supplier 105, the higher harmonics generated by a rush current is supplied to the standby power supplier 105. In more detail, only higher harmonics included in the power supplied to the main power supplier 108 are removed. Higher harmonics included in the power supplied to the standby power supplier 105 are not removed by the current waveform (e.g., rush current) 202 as depicted in FIG. 2. Accordingly, the video display apparatus may perform erratic operation because the DC power including the higher harmonics generated by the rush current is supplied to the standby power supplier 105.
In addition, the higher harmonics applied to the standby power supplier 105 may be transmitted to other apparatus through the standby power supplier 105 and a power line (not shown) and cause erratic operation of the other apparatus. For example, since the higher harmonics of the standby power has a bad influence upon the main power supplier 108, the video display apparatus may perform erratic operation.
As described above, the related art power supply device of the video display apparatus has various disadvantages. The related art power supply may cause erratic operations by applying the higher harmonics to the standby power supplier. In addition, in the related art power supply device of the video display apparatus, because the higher harmonics may be transmitted to other apparatus connected to the AC power line through the AC power input block, other apparatus may perform erratic operation.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.